Semiconductor device

Abstract

According to one embodiment, a semiconductor device includes a first electrode, a second electrode, a third electrode, a first nitride region, a second nitride region, and a third nitride region. The first nitride region includes Al x1 Ga 1-x1 N (0≤x1<1). The first nitride region includes a first partial region, a second partial region, a third partial region, a fourth partial region, and a fifth partial region. The second nitride region includes Al x2 Ga 1-x2 N (x1<x2≤1) or In y Al z Ga (1-y-z) N (0<y≤1, 0≤z<1, y+z≤1). The second nitride region includes a sixth partial region. The third nitride region includes Al x3 Ga 1-x3 N (x1<x3<x2). The third nitride region includes a seventh partial region.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a first electrode;   a second electrode, a direction from the first electrode to the second electrode being along a first direction;   a third electrode, a position of the third electrode in the first direction being between a position of the first electrode in the first direction and a position of the second electrode in the first direction;   a first nitride region including Al x1 Ga 1-x1 N (0≤x1<1), the first nitride region including a first partial region, a second partial region, a third partial region, a fourth partial region, and a fifth partial region, a direction from the first partial region to the first electrode being along a second direction crossing the first direction, a direction from the second partial region to the second electrode being along the second direction, a direction from the third partial region to the third electrode being along the second direction, a position of the fourth partial region in the first direction being between a position of the first partial region in the first direction and a position of the third partial region in the first direction, and a position of the fifth partial region in the first direction being between the position of the third partial region in the first direction and a position of the second partial region in the first direction;   a second nitride region including Al x2 Ga 1-x2 N (x1<x2≤1), the second nitride region including a sixth partial region, a direction from the fourth partial region to the sixth partial region being along the second direction; and   a third nitride region including Al x3 Ga 1-x3 N (x1<x3<x2), the third nitride region including a seventh partial region, the seventh partial region being located between the third partial region and the third electrode,   wherein
 the first nitride region directly contacts the second nitride region and the third nitride region, 
 the sixth partial region has a first thickness along the second direction; 
 the seventh partial region has a second thickness along the second direction; and 
 the first thickness is thinner than the second thickness. 
   
     
     
         2 . The semiconductor device according to  claim 1 , wherein:
 the third nitride region further includes an eighth partial region; and   a direction from the fifth partial region to the eighth partial region is along the second direction.   
     
     
         3 . The semiconductor device according to  claim 1 , wherein:
 the first thickness is not less than 1 nm and not more than 10 nm; and   the second thickness is not less than 20 nm and not more than 40 nm.   
     
     
         4 . A semiconductor device, comprising:
 a first electrode;   a second electrode, a direction from the first electrode to the second electrode being along a first direction;   a third electrode, a position of the third electrode in the first direction being between a position of the first electrode in the first direction and a position of the second electrode in the first direction;   a first nitride region including Al x1 Ga 1-x1 N (0≤x1<1), the first nitride region including a first partial region, a second partial region, a third partial region, a fourth partial region, and a fifth partial region, a direction from the first partial region to the first electrode being along a second direction crossing the first direction, a direction from the second partial region to the second electrode being along the second direction, a direction from the third partial region to the third electrode being along the second direction, a position of the fourth partial region in the first direction being between a position of the first partial region in the first direction and a position of the third partial region in the first direction, and a position of the fifth partial region in the first direction being between the position of the third partial region in the first direction and a position of the second partial region in the first direction;   a second nitride region including Al x2 Ga 1-x2 N (x1<x2≤1), the second nitride region including a sixth partial region, a direction from the fourth partial region to the sixth partial region being along the second direction; and   a third nitride region including Al x3 Ga 1-x3 N (x1<x3<x2), the third nitride region including a seventh partial region, the seventh partial region being located between the third partial region and the third electrode,   wherein
 the sixth partial region has a first thickness along the second direction, 
 the seventh partial region has a second thickness along the second direction, 
 the first thickness is thinner than the second thickness, 
 the third nitride region further includes an eighth partial region, 
 a direction from the fifth partial region to the eighth partial region is along the second direction, 
 the second nitride region further includes a ninth partial region, 
 the ninth partial region is located between the seventh partial region and the third electrode, 
 the second nitride region further includes a tenth partial region, 
 the eighth partial region is located between the fifth partial region and the tenth partial region, and 
 wherein:
 the tenth partial region is amorphous, or 
 a crystallinity in the sixth partial region is higher than a crystallinity in the tenth partial region. 
 
   
     
     
         5 . The semiconductor device according to  claim 4 , wherein:
 the eighth partial region has a third thickness along the second direction, and   the first thickness is thinner than the third thickness.   
     
     
         6 . The semiconductor device according to  claim 4 , further comprising a first insulating layer,
 the first insulating layer being located between the eighth partial region and the tenth partial region.   
     
     
         7 . The semiconductor device according to  claim 4 , wherein a direction from the sixth partial region to a part of the third partial region is along the first direction. 
     
     
         8 . The semiconductor device according to  claim 4 , further comprising a first insulating member including a first insulating region,
 the first insulating region being located between the third partial region and the third electrode.   
     
     
         9 . The semiconductor device according to  claim 8 , wherein the sixth partial region is located between the fourth partial region and a part of the first insulating member. 
     
     
         10 . The semiconductor device according to  claim 4 , wherein:
 the third electrode includes a p-type nitride; and   the p-type nitride includes at least one selected from the group consisting of Al and Ga and nitrogen.   
     
     
         11 . The semiconductor device according to  claim 4 , wherein:
 the second nitride region includes the Al x2 Ga 1-x2 N (x1<x2≤1);   the x2 is not less than 0.8 and not more than 1; and   the x3 is not less than 0.1 and not more than 0.35.   
     
     
         12 . The semiconductor device according to  claim 4 , wherein the first thickness is 0.5 times or less of the second thickness. 
     
     
         13 . The semiconductor device according to  claim 4 , wherein:
 the first electrode includes a first electrode face;   a direction from the first partial region to the first electrode face is along the second direction;   the second electrode includes a second electrode face;   a direction from the second partial region to the second electrode face is along the second direction; and   a distance in the second direction between a position of the first electrode face in the second direction and a position of the second electrode face in the second direction is 50 nm or less.